The vast majority of these studies show a gradual metallicity increase towards the core of the systems, with the maximum value spanning from half a Solar to slightly super-Solar values. This picture is qualitatively in line with the centrally peaked Fe abundance profiles that are typically found in relaxed clusters [1]}, [2]}, [3]}, [4]}, [5]}. Quantitatively, samples including groups and clusters are valuable to provide comprehensive comparisons. For instance, [6]}, [7]} studied 28 galaxy groups and concluded that (i) systems with lower level of feedback impact are on average more metal rich within \(\sim \) 0.03\(R_{500}\) , and (ii) systems classified as "cool-cores"In [6]}, a "cool-core" group is defined as such when its temperature profile shows a clear central decrease out to at least \(\sim \) 0.1\(R_{500}\) . This definition is of course arbitrary and may differ from other proposed ones. are, on average, more enriched in their cores (\(\sim \) 0.1\(R_{500}\) ) than clusters. Similar conclusions were reached for 43 Chandra groups (re-) analysed by [9]}, although a significant increase of average metallicity with group temperature (hence, mass) was also reported. More recently, results from the CHEERS sample – consisting of 21 "groups/ellipticals" and 23 "clusters"In [3]}, a "group/elliptical" is defined as such when the mean temperature of the system within 0.05\(R_{500}\)  does not exceed 1.7 keV. Here again this definition is arbitrary and a given rich group could be defined as a poor cluster in other studies. – suggest for instance a similar decreasing profile for both types, with the former being on average slightly less enriched than the latter [3]}. On the other hand, [4]} analysed a sample of 207 systems and concluded that, despite their scatter, on average "groups/ellipticals" (defined in the same way) have a slightly higher metallicity than clusters within 0.1\(R_{r500}\) . A recent re-analysis of the CHEERS sample within \(0.1R_{500}\)  using an updated SPEX version (v3.0.4, also more consistent with the apec v3.0.9 version used in [4]}) find more consistent results, with groups being at least as enriched as clusters within that limit [14]}. More detailed discussions and interpretations on the absolute metallicities in groups. vs. more massive systems is addressed in Sect. REF  (observations) and Sect. REF  (cosmological simulations).
